PALUD1NA TRANSVERSA. 33 



seem like equidistant corrugations of the epi- 

 dermis ; having no effect whatever in modify- 

 ing the calcareous surface, upon which no trace 

 of them is exhibited." Say. 



I think Paludina transversa rests upon too 

 slender grounds to be admitted as a distinct 

 species. I give figures of the original speci- 

 mens in the Academy's collection, and insert 

 Say's descriptions and remarks here. 



PALUDINA TRANSVERSA. " Shell transverse, depressed, 

 orbicular ; spire convex ; whorls three and a half; with nu- 

 merous minute, slightly elevated, revolving lines ; suture not 

 widely indented ; body whirl very convex, short ; umbilicus 

 small ; operculum pale fulvous. 



" Greatest width two-fifths of an inch. Inhabits Louisiana. 



" We obtained two specimens in the marshes near New 

 Orleans. It is much wider in proportion to the length than 

 any other species I have seen, excepting in this respect even 

 M. subglobosa, Nob., and especially P. intertexta, Nob., of 

 which latter, in fact, I at first supposed it to be the young, 

 in consequence of its rotundity, and the similarity of its ca- 

 pillary lines ; but, inasmuch as the number of its whirls is 

 nearly the same, whilst the magnitude differs so greatly, I 

 have separated it as a different species." Say. 



REFERENCE TO PLATE 10. 



Figures 1 and 2 represent a large shell from New Orleans; 

 a, opercle ; 3,4, are drawn from a South Carolina specimen ; 

 5, 6, represent Paludina transversa, Say, and 7, 8, P. sub- 

 globosa, Say. 



F5 



